Model Boat Mayhem - Forum

Please login or register.

Login with username, password and session length.
Pages: 1 [2]   Go Down

Author Topic: Stepper motors  (Read 7106 times)

Umi_Ryuzuki

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 1,118
  • Location: PDX, OR USA
    • Models and Miniatures
Re: Stepper motors
« Reply #25 on: June 25, 2013, 05:32:37 AM »



Me too..... but it does make a bit more sense after the 4th or 5th read and a long sit down :)
Just remember that computer you are using now probably did the same thing to you when you first got it.

I'll have to read it at least twice that many times...

I know there is potential here for stepper motors and arduino control,.. :((

http://youtu.be/g-z-mKjl6z8

Hellmut1956

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 114
  • Best Hobby in the World!
  • Location: Mammendorf, Germany (near Munich)
Re: Stepper motors
« Reply #26 on: June 25, 2013, 06:31:56 AM »

This is why getting a StepRocker board and playing with it makes the transition from theory to practical use much, much easier. Connecting the board to a PC and a Stepper motor to it after having installed the LIBUSB USING the filter for installation really makes the difference. I have presented the links where you can buy it!


Soon Trinamic will introduce the motionCookie called component and a board similar to the StepRocker that will be even more usefull. Specially you will learn why often stepper motors do not work!
Logged
Best regards Hellmut

vnkiwi

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 1,600
  • Location: SE Asia
Re: Stepper motors
« Reply #27 on: June 25, 2013, 06:42:36 AM »

Keep up the good work, always wanted to know how they work, and why
cheers
vnkiwi
Logged
If it ain't broke. Don't fix it !

Neil

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 1,385
  • Location: near Fleetwood
Re: Stepper motors
« Reply #28 on: June 25, 2013, 09:47:48 AM »


It still does  O0 O0 %% %%

if I could get away with an abacus...........I WOULD {-) {-) {-) {-)
 
I'm sorry, but I'm a model maker, and not an electronics wiz.......I don't even know what  95% of the names or terms mean and at my age............sadly too long in the tooth to even start learning. lol %% %% %% %%
Logged

Hellmut1956

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 114
  • Best Hobby in the World!
  • Location: Mammendorf, Germany (near Munich)
Re: Stepper motors
« Reply #29 on: June 25, 2013, 10:56:21 AM »

I will be totally honest, as I am always trying to be! I have the StepRocker card not behaving like I was used to and so i am investigating this.





In this picture you can see the setup i have made in my brand new electronics working desk. To the right you see the unit that allows me to connect fixing with screws the cables and measurement equipment to the power supply. It also has a total of 5 small switches which allow me to switch on and off up to 5 different voltages, those are the black stuff between the yellow and the green banana jacks on the rear board. Just for completeness, the board in the front of this unit has to large screws to which I can feed the desired voltage to connect the battery charger!


In the middle back of the picture are to multimeters, the large one to the right is connected in series to the positive pole of the power supply of the StepRocker board and set to measure current up to 10 A! The smaller one to the right is connected to the power supply unit to indicate the voltage applied to the StepRocker board.


To the left, a bit in front of the multimeters is the StepRocker board and to the right of the board is the connector, to which i connect the stepper motor. This way i can replace the stepper motors relatively easily! A stepper motor with 8 connecting cables offers the user another possibility and i do use this opportunity to introduce you to it! Remember always to cables, a pair, will show a very low resistance when measured with the Ohmmeter, demonstrating this way that they belong to one set of coils. So having 8 cables, means that I do have 4 set of coils in the stepper motor. This means that i have to connect them in a way to reduce the number of cables to 4, as this is the number of cables that can be connected to the any stepper motor controller. it is now posible to connect the coils in 2 different ways. You can either connect them in series, what means that you connect 2 coils by connecting one cable from each to the other, the Ohmmeter will show twice the resistance as now the resistance would be measured of the cable that make up both coils. The other way is to connect them in parallel, this means connecting 2 pairs of cables coming from 2 coils in such a way to the stepper motor controller that they end up being connected in parallel to the same 2 ports of the 4 of the controller:





I am using this picture, as it shows the diagram of a stepper motor with 2 pairs of coils, but is intended for another message! At the poles of the coils you see colors named, which allow to identify the right cables. Lets take the diagram in the second row lo the left. here you see the coils connected in series, so the the stepper motor controller we just connect "black" and "green" ones and the "red" and "blue" ones to the motor and connect the left cables as shown in the graph.
To connect the coils in parallel we would connect the "black" and the "Orange" ones to one jack of the controller, the "yellow" and "green" one to the next, "red" and "brown" and "white" and brown" finally to the 4th connector.


What is the difference? Well. connecting the in series gives you a bit more torque, connecting in parallel makes the signals more stable and in consequence the stepper motor will operate a bit smoother and in consequence be able to be operated a bit faster. You find this graph or the relation of the colored cables to the coils in the datasheet of your stepper motor. If you do not find a datasheet you might guess the right pairing by test and failure. Should you fail to connect them in a way that the pairing of the coils is as shown in the picture you will notice a problem when trying to operate the stepper motor. One additional piece of information that might help you to solve problems you might face when trying to operate your stepper motor. That is definitely one of the purposes of this tutorial!





Now I have activated the switch applying the power supply to the StepRocker. The current reading shows 0.08 or 80 mA and the tension reading 26.1 volt!





Then I go to the Windows Device Manager to verify the StepRocker board has been identified correctly and assigned to which COM, here COM 8! The reason for this is that I first had huge problems to install the driver. It actually made my 2 PCs inoperative until i found out how to deinstall the driver. The reason is that if you try to install the driver LIBUSB the normal way it will replace all drivers in all USB ports so that everything connected to USB stops working! A year later finally a filter was made available that allows to assign just the port desired the LIBUSB driver by using a software filter that is part of the download when the latest version of LIBUSB is downloaded. So, please, be cautious and better ask twice for support to make it right!





Next I start the IDE from Trinamic, links to download the software for free where presented here before and open the menu item Setup>>options which opens a small window and when clicking on the tab "Connections" it will show what can be seen in the last image and you verify that COM 8 is selected.





Then you click on the icon that shows a hand pointing upwards or select the menu item "TMCL>>Direct Mode..." to get the window open as shown in the picture. I have extensively introduced the functionality of this window, the GUI, before. please verify you have setup the parameters i mentioned above as shown above, the write into the text box for "Value" on the left the value of 512 and click on execute to have the stepper motor start rotating!


http://www.flickr.com/photos/hellmut1956/9132095015/


When you click on the link above you will be able to see my first video in this tutorial with the stepper motor rotating slowly at a velocity set to 419 out of -2047 to +2047 possible velocity values, approximately 1/4 of the maximum velocity value, but far away from the maximum speed I can reach!

Logged
Best regards Hellmut

Hellmut1956

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 114
  • Best Hobby in the World!
  • Location: Mammendorf, Germany (near Munich)
Re: Stepper motors
« Reply #30 on: June 25, 2013, 11:05:11 AM »

Neil, I will complete the 57 years on earth this year, so it is never too late. But many roads lead to Rome and I am autodidact. Using the software and using the videos I start presenting now, will show how easy it is to work with stepper motors. The theory is important to help to understand when problems pop up to find a solution. The first video presented here shows how easy it is to operate a stepper motor. On the other hand, reading the posts here on the forum I must say that many techniques applied there are much more difficult and demanding than those to just operate software to make the stepper motor do what we want it to do. I believe that selfbuild electronics is much simpler to use as soon as we stop giving it a nimbus and feeling intimidated by it. So just keep watching the videos as I will be publishing them and now everybody knows, when you ask a question about a term, that you are a brave boy facing a challenge! But even so, this is for those that want to know more about stepper motors and not all need to be interested in!
Logged
Best regards Hellmut

Hellmut1956

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 114
  • Best Hobby in the World!
  • Location: Mammendorf, Germany (near Munich)
Re: Stepper motors
« Reply #31 on: June 25, 2013, 11:50:05 AM »

http://www.flickr.com/photos/hellmut1956/9134542234/


This is now the video with the parameters ramp_divisor and pulse_divisor changed to the value of "1" so the completion of a 360 turn is 1 second, or 1 Hz at a velocity setting of 419! To Neil, this is the name the company Trinamic has given to a speed setting parameter that I do describe in detail above. One of the issues that helps a lot is to remember that "terms" have 2 functions! One is to make sure that so called "no experts" have not a clue what it is all about and do believe it is beyond their abilities with the side effect to promote job security! T+he second and serious one is that the use of well defined terms removes possible ambiguities in what is being said and there for it enables you to express yourself clearly. For us amateurs the first reason listed helps to make us aware that all experts are ruled by general laws of physics and that their is little magic. So loose the fear and be opened minded and ask when you miss something. Not asking when not understanding is foolish, questions never are!


On the other hand, when getting into a new field of knowledge I always try to catch the big picture and i never mind asking the eventually most foolish questions. I am willing to give some terms the character of a blackbox and dwelf into their meaning later. I confess I have little knowledge about the full meaning and of the full implication of the terms "ramp-divisor" and "pulse_divisor", so what! i do have a guess resulting from the names of those 2 terms. They have to do with computations done around the topics of the "ramp characteristic", remember there is a function that I introduced to you using the video of the glass half filled with water and being moved, once following a trapezoidal speed profile and once the "S-ramp" shape. The second term related to pulse I guess has to do with other computations that somehow impact the speed of stepping of the stepper motor. Signal pulses make the stepper motor do its steps, only when the 2 parameters presented here have the value of "1" the formulas, I passed into an Excel spreadsheet, does compute the rotating speed and the rpm for the stepper motor correctly!


Why am I writing so much about now having the knowledge about 2 terms? I want to exemplify with this 2 parameters how to face constructively the lack of knowledge when dwelling into a new topic to prevent from being blocked as neil was so brave to point out, that he had this problem and how I do handle this situation. May be it helps. But be sincere, is it that difficult to change the value of one or two parameters and watch what is the result of those changes as demonstrated in the last videos published?
Logged
Best regards Hellmut

Hellmut1956

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 114
  • Best Hobby in the World!
  • Location: Mammendorf, Germany (near Munich)
Re: Stepper motors
« Reply #32 on: June 25, 2013, 03:03:39 PM »

My god, it takes forever to upload a video!
Logged
Best regards Hellmut

Hellmut1956

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 114
  • Best Hobby in the World!
  • Location: Mammendorf, Germany (near Munich)
Re: Stepper motors
« Reply #33 on: June 25, 2013, 03:54:20 PM »

Here a shield for Arduino that can use some of the features from Trinamic I present in my tutorial!


http://www.watterott.com/index.php?page=search&page_action=query&desc=on&sdesc=on&keywords=Trinamic&x=7&y=4
Logged
Best regards Hellmut

Hellmut1956

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 114
  • Best Hobby in the World!
  • Location: Mammendorf, Germany (near Munich)
Re: Stepper motors
« Reply #34 on: June 25, 2013, 04:03:02 PM »

Finally the video was uploaded onto Youtube. it shows the impact of the velocity setting on the speed of the stepper motor.


http://youtu.be/nKfdMpfcg4A


This video focuses on the rotation speed of the stepper motor, keeping the microstep setting to 256 microsteps per full step. Remember, every pulse, that means a certain pattern of tensions applied to the 4 connections to the stepper motor, makes the stepper motor to one step, microstep resolution set to 256 microsteps means the stepper motor is stepping at every pulse just one microstep! The next video, is just uploading to Youtube, will show the impact of the microstep resolution on the rotation speed of the stepper motor. To be able to reach the full step setting the velocity parameter will just be set to "10" out of "2047" possible fastest velocity setting, means just about 4% of the maximum velocity and how the parameter "microstep resolution" will impact the rotation speed of the stepper motor! You can guess that the speed setting to be just about 4% of the maximum shown in this last video, changing the microstep resolution from 256 to full step, will just by calculation:


256 * 4% = 1000%, or 10 times the rotation speed maximum we saw on this last video.
Logged
Best regards Hellmut

Hellmut1956

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 114
  • Best Hobby in the World!
  • Location: Mammendorf, Germany (near Munich)
Re: Stepper motors
« Reply #35 on: June 25, 2013, 05:26:11 PM »

Now as promised the video demonstrating the stepper motor while changing the microstep resolution:


http://youtu.be/3A2zNbMxW5A


One good feature of this video is that at the end I try to increase the velocity setting from "10" to "15" which makes the motor stall and stop stepping/rotating and making a lot of noise and vibrating heavily! When i tried to operate this stepper motor with at stepper motor controller just being able to deliver full steps i was never able to get the stepper motor stepping and I believed the error was with me,  not knowing how to operate the stepper motor controller. Now, after experiments with the StepRocker and applying twice the voltage, not 12 VDC, but 25 VDC i saw in my experiments that that motor would never work with the old controller.


In the next video I will combine the microsteps resolutions and the velocity settings to achieve the highest possible rotation speed of the stepper motor. Let me reveal upfront that even that will not be the maximum achievable. This will only happen after I use the step interpolation function of the controller. With this function I do set the microstep resolution to 4, means 16 microsteps per full step. The function will than generate in hardware 16 additional microstepping pulses in the time each of the microsteps happen an accelerating the stepping rate by a factor of 16.
Logged
Best regards Hellmut

Hellmut1956

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 114
  • Best Hobby in the World!
  • Location: Mammendorf, Germany (near Munich)
Re: Stepper motors
« Reply #36 on: June 25, 2013, 05:26:28 PM »

Sorry, double posting due to an server error message handling! Moderator, I would welcome deleting this post!
Logged
Best regards Hellmut

Hellmut1956

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 114
  • Best Hobby in the World!
  • Location: Mammendorf, Germany (near Munich)
Re: Stepper motors
« Reply #37 on: June 26, 2013, 05:44:23 PM »

Hi friends, the video is right now being uploaded to YouTube and will be published here as soon as available, still so YouTube already gives me the link to the video:


http://youtu.be/nopezWBlDL0


Lets start with the result! I was surprised how fast the stepper motor did rotate! The last setting where the motor did not stall was at a velocity of 1300. I did enter the settings into the spreadsheet and got the following results:


Full step frequency: 158.691,4 Hz, at 200 full steps per 360 turn


Turns per second: 793.5 Hz which results in an


RPM: 47.607,4


This is pretty high for a stepper motor.


As this speeds was achieved at a supply voltage of 25,1 VDC and the supply voltage on my model sailship resulting from the use of 12 LiFePO4 batteries will be of more than 40 VDC when the batteries are full and then drop down to a minimum of 24 VDC, means that most of the time my sailboat will allow for much higher speed!


But remember, a stepper motor looses torque as it gets faster. The drum for the sheet on my model sailboat has a circumference length of 400 mm and the maximum sheet displacement will be of 8,4 meters, which results in just 21 turns of the drum which at the above speed would be just 0,0265 seconds or 26,5 ms! I plan to have the 8,4 meters of sheet to be moved in just 1 second or about 1/40 of the above speed is needed for this!


Still so, when I finally fix my drill mill, I will make experiments to determine a speed profile that offers the best compromise between speed and low stress of the sheet and the blocks. next i will make short videos to introduce you to the operation of a small 28x28 mm stepper motor and of the stepper motor from a CD drive. I hope you will have found this short tutorial on stepper motors useful and now I am ready for any questions that might pop up!
Logged
Best regards Hellmut

Hellmut1956

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 114
  • Best Hobby in the World!
  • Location: Mammendorf, Germany (near Munich)
Re: Stepper motors
« Reply #38 on: June 26, 2013, 06:11:03 PM »

The last video might be boring for those that do not understand stepper motors. But getting a stepper motor to rotate so fast it only stalled at a velocity setting of 1350, executing perfect and silent and with practically no vibration at a velocity setting of 1300 achieving close to 800 Hz, 800 360 turns per second, or 51200 * 793.5 = 40.6 Million steps per second is amazing! I have learned a lot during the work on this videos and for those of you that might watch them it will become evident how easy it it to make the stepper motor do the job shown here.


The next part of the exercise will be to have the stepper motor move between assigned step positions, to experiment with the parameters that do influence the trapezoidal speed profile and then to work myself into the stallguard function that offers security allows for fail safe behaviour to be achieved and the other cool energy saving functions. For this i plan to build some setups and as a consequence the tutorial will continue after a longer break!
Logged
Best regards Hellmut

vnkiwi

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 1,600
  • Location: SE Asia
Re: Stepper motors
« Reply #39 on: June 26, 2013, 08:27:43 PM »

look forward to the next installment
cheers
vnkiwi
Logged
If it ain't broke. Don't fix it !

Hellmut1956

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 114
  • Best Hobby in the World!
  • Location: Mammendorf, Germany (near Munich)
Re: Stepper motors
« Reply #40 on: August 15, 2013, 05:13:48 PM »

I have been working on the tutorial in the versions published in german and Spanish and would like return here and try to help those that I have lost on the way to catch up!First allow me to give you a link to a shield for Arduino that uses Trinamic parts. This just for completeness! But lets jump onto the challenge of getting those of you willing and open minded to jump again on the wagon!First, to my believe a tutorial is different from a cookbook in that you get background information to be able to get deep into the subject! Steepers face such a luck of knowledge, that to supply a set of basic information is one of the goals of this tutorial, but now lets shortly move to the cookbook mode!Here you can buy the card used in the videos I will present called stepRocker. the site is in German but the site and the product description is in English. I have selected the destination country to be UK. Using this card, size:
    • Length
    • 85 mm
      • Width
      • 55 mm
        • Height
        • 29 mm


      at a price tag of 66.05 plus shipping you can actually use the card to manage your stepper motor in your model the same way I start demonstrating in the videos. The company you would be buying from is a serious company, so you do not have to worry about a fraud! At the same site under this link you can find their extensive offer of high quality stepper motors! This stepper motor at just 16,90 surely is a good choice to experiment with!


      So I use this opportunity to just introduce two kind of stepper motors. One is an hybrid stepper motor like you find in the last link:





      The second is the kind of bipolar stepper motor you find in printers and CD-drives!








      The first of the two less expensive stepper motor was gained by cannibalizing a CD-drive. This motor is used to move the reader along the radius of the CD and it also works fine with the stepRocker card.


      Hybrid stepper motors are the ones used i.e. in CNC applications and I use such an stepper motor in my videos that I will later be placing 2 of those in my sailboat model, presented under the name carina in Building from scratch in this forum!. On the picture the motor is presented with its cons!


      The permanent magnet motors are cheaper and are those we find in printers and CD-Drives! So far this short introduction to 2 types of bipolar stepper motors!





      This picture nicely explains what kind of cabling you find in stepper motors, focusing exclusively on bipolar motors. let me advice you, that you always will find also unipolar stepper motors in applications like printers. Those cannot be used and are not the topic neither of this "cookbook" within the tutorial, nor will I deal with them in my tutorial! You can identify the cables, if you do not have a datasheet of the motor by measuring the resistance between the cables. If it is infinite, than those 2 cables are not connected, if you can read a resistance value, than there are 2 choices depending if you have 4 or 8 cables coming out of the motor.
      In a bipolar stepper motor with 4 cables coming out of it it is simple, you can identify "phase A" and "phase B" circuits and so connect it properly, if you have 8 cables coming out of it, it is still simple, but it offers you one additional choice, this is good! :)


      The 3rd picture horizontally  shows this option and the 2 last configuration pictures in the graph explain what I am addressing. Connecting the the "middle cables" puts 2 coils in series like in the 6th picture and in parallel in the last picture. In series you can gain more speed, in the parallel option you get more stability. I choose the parallel option to connect the stepper motor in the video will let you watch next.


      http://youtu.be/nopezWBlDL0


      In this video I have set all parameters I am playing with to best settings to achieve maximum rotation speed. When you listen to the noise from the motor you will be able to hear every time I do set a higher speed. But you will also be able to notice the noise and the kind of noise that the stepper motor will make. This variance for me needs explanation and understanding of its causes and this knowledge the tutorial will give you as soon as I can catch up those getting lost on the way! if you notice, it is kind of random when the motor makes noise and when not and what kind of noise it makes. It is definitely not proportional to the step frequency! So please ask the questions as to what you do not understand or where I loose you. But with the stepRocker card it is trivial to control a stepper motor, by just setting values to parameters. In this video after having setup other parameters i just change the "velocity setting", which is the stepping frequency supplied to the motor and which can take any value from "0" to "2047". keep this in mind as I call the values I am setting as the video goes and the stepper motor accelerates! But please remember, different from normal motors I can have the stepper motor stop at any chosen position, 51200 position choices at every 360 turn!
Logged
Best regards Hellmut

Hellmut1956

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 114
  • Best Hobby in the World!
  • Location: Mammendorf, Germany (near Munich)
Re: Stepper motors
« Reply #41 on: August 22, 2013, 07:00:04 PM »

Dear friends, it takes perseverance, plenty of sweat and tears and a lot of time to understand what is being written, specially when it is in area, electronics, where many feel uncomfortable with. But recently I was reviewing old threads from the days I started to study the topic and I read a feed back from a real robotics electronics expert, no irony, I real mean he is an expert and has given me over time many valuable tips, about the achievable speed with a stepper motor of the kind I used in a video where I demonstrated an amazing speed. This expert in 2008 wrote that the maximum speed allowed with no load to the stepper motor about 1000 steps per second or 5 full 360 turns per second and only about 200 steps with the motor working under load, or just 1 360 turn per second.


http://youtu.be/nopezWBlDL0


In this video you an see what the latest components make possible 5 years later in 2013!



Logged
Best regards Hellmut
Pages: 1 [2]   Go Up